"Clearly that behaviour is unacceptable in any football ground in the country and at Millwall we will ban the individuals for life and we hope that Sky will pass the footage to the police so that further action can be taken.

"Sadly racism exists in our society and certain individuals want to bring it into football grounds. It's down to us in football do to more.

"That day against Leeds obviously there was an allegation of abuse made online initially. We investigated it straight away.

"We interviewed stewards, police, players, we looked at the TV footage too as it was live on Sky.

"After speaking to the player who had the alleged abuse at him during the day, he said that he heard no abuse on the day so that was basically at that point the end of the investigation - although we're going to open it again now."

Meanwhile, Marvin Sordell has claimed he was "surprised" but not shocked that racism existed in football.

The Bolton forward claimed on Twitter that he was taunted by fans at Millwall in October as he warmed up as a substitute.

Sordell who represented Great Britain at the London 2012 Olympics, has faced racial abuse on social media websites.

He said: "We're a developed, multicultural society. It's surprising it can still go on - but it doesn't exactly shock me.

"We can't be silent about it. We need to make people aware that there is a problem going on and only when people are aware of the problem can it be sorted out."